PLC concept and strategy
The PLC of the Plastic Application implements the control functions of the Plastic Framework (TF8540 & TF8560) in a manufacturing-oriented approach. The framework (in particular TF8560) itself is detached from this approach and implements core functions (CoreFunctions) for plastics technology. For example, a general point to point movement or cam plates are provided. In addition, the general axis interface I_AxisBase offers the possibility to implement the production-oriented application algorithms without specifying the drive technology. This results in the classes (FBs) of the Plastic Base Application library.
As an example of the concept, the wall thickness control (WTC) can be considered here:
This component of a blow molding machine is fundamentally based on the cam core function provided by TF8560 (Camming). For the user, this is often of secondary importance, since he wants to integrate the functions based on it, such as Start wall thickness profile or Move to test position, into his procedure. This step is pre-implemented by the Plastic Base Application so that the scope of tasks to be completed to the finished machine is minimized as much as possible.
Other concept points are discussed in more detail in the following subsections:
Topic | Description |
|---|---|
Communication path between PLC and HMI | |
Use of inheritance for more efficient use of redundant code and easier function extension | |
Structure of interface in Plastic Base Application and programming with interfaces to extend control flexibility | |
Scheme of designations to ensure compatibility | |
Initialization of references, parameters and data | |
Data handling at machine and product level | |
Explanation of the TwinCAT project |